Gabriel Leung became the fortieth Dean of the Li Ka Shing Faculty of Medicine in August 2013. Leung, a clinician and a respected public health authority, concurrently holds the Chair of Public Health Medicine. Previously he was Professor and Head of Community Medicine and served as Hong Kong’s first Under Secretary for Food and Health and fifth Director of the Chief Executive's Office in government.

Leung specialises in the field of public health medicine, a statutorily accredited specialty that covers the full range of public health sciences and their constituent disciplines.

Within the broad scope of public health medicine, his major interests revolve around topics that 1) have major population health impact locally, 2) where Hong Kong is a reliable and unique epidemiologic sentinel for mainland China, or 3) where Hong Kong is particularly endowed and best placed to address the fundamental science at hand. As such his research crosses the traditional boundaries of individual disciplines or fields of enquiry.

Specifically, for over a decade, his team has leveraged on several ongoing large-scale cohort studies, namely the "Children of 1997" birth cohort, Elderly Health Services cohort, Guangzhou Biobank Cohort Study and FAMILY cohort, to test a series of novel hypotheses based on a socio-historical perspective of life course epidemiologic theory. These investigations have proposed novel insights about the fundamental biologic pathways leading to common non-communicable diseases, namely cardiovascular disease and Type II diabetes, with global health relevance.

Leung established and directed the University’s Infectious Disease Epidemiology Group since the time of the 2003 SARS epidemic and led Hong Kong government’s efforts against pandemic H1N1 in 2009. He continues to co-head the School’s WHO Collaborating Centre for Infectious Disease Epidemiology and Control. Current priorities focus on field studies and modelling of influenza (supported by US NIH), hand-foot-and-mouth disease (in collaboration with China CDC), human papilloma virus and other infections of public health significance. His team of investigators is now recognised as one of the leading epidemiologic laboratories in the field of influenza research.

A third and final component of his research programme is health systems and policy research, where his team has been responsible for national health accounting for the Hong Kong government and as consultant to governments throughout the region. It has also been a major contributor to the EQUITAP and Global Network for Health Equity projects (sponsored by EU FP7 and IDRC), assessing the equity performance of health systems across more than a dozen countries in the Asia Pacific and globally respectively. Leung has also pioneered the development of cost-effectiveness, health systems, financing and policy research in Hong Kong and around the Asia Pacific region. From 2010 until 2014, he served as inaugural Chair of the Asia Pacific Observatory on Health Systems and Policies, a multipartite partnership of governments, development agencies and the research community. Most recently his team has been commissioned by government to develop and evaluate screening strategies for breast and colorectal cancer prevention, as well as to undertake projections to inform human resources for health planning.

Leung maintains a substantial teaching commitment in the undergraduate medical and postgraduate public health curricula. His teaching has been recognised by the award of the University Teaching Fellowship and the Faculty Teaching Medal, respectively the highest honour for teaching achievements conferred by the University and the medical school. He has mentored 15 PhD and 4 MPhil research postgraduates to date.

He is an honorary consultant in family medicine and primary care of Queen Mary Hospital/Hong Kong West Cluster and attends a weekly clinic.